Low network throughput on i.MX28

[joerg.krause@embedded.rocks (Jörg Krause)]

On Wed, 2016-11-02 at 09:24 +0100, Stefan Wahren wrote:
> Am 02.11.2016 um 09:14 schrieb J?rg Krause:
> > On Sat, 2016-10-29 at 11:08 +0200, Stefan Wahren wrote:
> > > > J?rg Krause <joerg.krause@embedded.rocks> hat am 29. Oktober
> > > > 2016
> > > > um 01:07
> > > > geschrieben:
> > > > 
> > > > 
> > > > You mentioned [1] an optimization in the Freescale vendor Linux
> > > > kernel
> > > > [2]. I would really like to see this optimization in the
> > > > mainline
> > > > kernel.
> > > > 
> > > > Did you ever tried to port this code from Freescale to
> > > > mainline?
> > > 
> > > Yes, i tried once but i was frustrated soon because of the lot of
> > > required
> > > changes and resulting issues.
> > 
> > I got the PIO mode working for the mxs-mmc driver. For this I
> > ported
> > the PIO code from the vendor kernel and removed the usage of the
> > DMA
> > engine entirely.
> 
> Good job

Thanks!

> > 
> > Testing network bandwidth with iperf, I get about ~10Mbit/sec with
> > PIO
> > mode compared to ~6.5Mbit/sec with DMA mode for UDP and about
> > ~6.5Mbit/sec compared to ~4.5Mbit/sec with DMA mode for TCP.
> 
> And how about MMC / sd card performance?

Can't tell as my custom i.MX28 board does not have a SD card interface.

I will share the code after doing some cleanups and further tests so
you might test it as well.

J?rg